This invention relates to amplifiers.
More particularly, the invention relates to an audio amplifier installed in an automobile or other vehicle.
In a further respect, the invention relates to a system for turning a radio audio amplifier in a vehicle on or off.
In still a further respect, the invention relates to a system for installing a radio audio amplifier in a vehicle at a location remote from the radio and for sensing voltage in the radio speaker wires to turn the amplifier on and off.
An audio speaker is a device that receives a signal and produces sound. The signal received by a speaker typically, but not necessarily, is an electric signal produced by an audio amplifier. The speaker receives the amplifier signal and produces vibrations which produce sound.
High power audio amplifiers are frequently added to an entertainment system in an automobile or other vehicle to amplify the audio output from a radio mounted in the vehicle. These high-power amplifiers are usually housed in a chassis or enclosure different from the radio, and they are frequently mounted in a location that is not near the radio. When the vehicle is turned off and the radio is not in use, a means must be found to deactivate the amplifier so that the amplifier will not drain the vehicle""s battery.
Automobile radios typically provide a xe2x80x9cremote outputxe2x80x9d signal that supplies a signal voltage. The strength of the signal voltage is equal to the battery voltage. The remote output signal is used to activate and deactivate a power antenna, an externally-mounted amplifier, and other remote devices associated with the radio. A separate xe2x80x9ccarrierxe2x80x9d wire is connected to and intermediate the radio and remote device to receive and carry the remote output signal from the radio to the remote device. A disadvantage associated with using such a carrier wire is that if a remote device is incorporated after the radio has been installed in the vehicle, the remote output signal is not usually accessible without removing the radio from the dash, an expensive and time-consuming operation, which adds to the installation cost for the remote device.
Many amplifiers accept as their input signal the voltage on the radio speaker cables that are already installed in a vehicle. Some manufacturers have attempted to turn a remote amplifier on and off by detecting the presence of an audio signal on these speaker cables. A disadvantage of this procedure is that when the vehicle radio is turned on or off, the clicks and thumps that normally occur on the speaker cables may be misinterpreted as a valid audio signal, activating the remote amplifier and possibly damaging a loudspeaker connected to the remote amplifier.
Accordingly, it would be highly desirable to provide an improved apparatus and method for turning on and off a remote amplifier mounted in a vehicle and associated with a radio also mounted in the vehicle.
Therefore, it is a principal object of the invention to provide an improved method and apparatus for installing in a vehicle an amplifier which is remote from but is operatively associated with a radio also installed in the vehicle.
Another object of the invention is to provide an improved method and apparatus for turning an amplifier on and off.